A. Field of the Invention
This invention relates to telephone systems and in particular to multiplexing line circuits to a group of transmit and receive highway lines coupled to a central switch.
B. Prior Art
Centrally switched telephone systems are used in business, industry and government. Multiplexers are typically used to connect a large number of phones to a limited number of conventional communication lines. Time division multiplexers provide this capability by periodically allocating a time slot to each of the telephones they will service. In the prior art, multiplexers performed time slot decoding one slot at a time. Each telephone circuit required a separate time slot decoder device to properly phase the data transmissions for the telephone connected to that circuit. This increased the complexity of the multiplexers in two respects. First, more hardware was required to construct the multiplexer. There was a one-to-one correspondence between the number of telephones and the number of time slot decoder devices contained within the multiplexer. Second, the complexity of the software which controlled the telephone system was increased since this central control mechanism had to assign and keep track of time slots for each of the telephones.